It should be noted though that there is danger of a regression test failure.
Some coffee machines would not accept cups higher (vertically larger), so the
increasement in buffer size would need to go to circular dimensions, i.e. the
radius.
Luckily, the amount of extra buffer space needed is relatively small, otherwise
we’d end up with a Müesli cup instead…

When applying a normal amount of espresso, cane sugar, cocoa powder, and
steamed milk to a Grml coffee cup, it will overflow. While this is not an
exploitable bug, it can be pretty messy to clean up.
Futhermore (see attached screenshot, taken after freeing some of the buffer)
junk data can be left on the outside, which reduces the drinking experience.
Proposed fix: enlarge the cup.